1998 Fiscal Year Final Research Report Summary
Protein chemical analysis of amyloid beta-protein in the brain of early stages of beta-amyloidogenesis
| Project/Area Number |
09835003
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
老化(加齢)
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| Research Institution | The Universi of Tokyo |
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Principal Investigator |
MORISHIMA Maho The Universi of Tokyo, Granduate School of Medicine, Instructor, 大学院・医学系研究科, 助手 (50204722)
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| Project Period (FY) |
1997 – 1998
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| Keywords | amyloid beta-protein / Alzheimer's disease / low-denity membrane domains / ELISA |
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| Research Abstract |
1. We have examined amyloid beta-protein (Abeta) deposition in many autopsied human brains using two-site ELISA and immunocytochemistry, and found that Abeta accumulates in the brain during normal aging. The level of Abeta in the brain correlated well with the abundance of senile plaque. In addition, Abeta accumulation which could be detected by ELISA preceded immunocytochemically detectable Abeta deposition in the brain.
2. The present ELISA system captured SDS-dissociable A13 but not SDS-stable Abeta dimer. Western blot analysis of the brains in which the level of Abeta was below the detection limit of ELISA showed that many of such specimens contained SDS-stable Abeta dimer, but not SDS-dissociable Abeta monomer. The results indicate that SDS-stable Abeta dimer accumulates in the brain at the very initial stages, raising a possibility that SDS-stable dimer plays important roles in beta-amyloidogenesis in the aged human brain and the neurodegeneration of AD.
3. Fractionation of the deposited Abeta species in normal aged brains by CsCl isopycnic density gradient centrifugation showed that a part of the Abeta was fractionated into the low-density membrane fraction. From analyses of their electrophoretic mobilities and reactivities with various Abeta antibodies, however, these Abeta molecules were not likely to be the same as GM1 ganglioside-bound Abeta found in the Down's syndrome brains.
4. We have shown that intracellular A13 is present in the insoluble fractions as well as in the soluble fractions of human neuroblastoma cells. The insoluble fraction appeared to contain also SDS-stable Abeta dimer. Approximately half an amount of the insoluble Abeta was associated with caveolae-like low-density membrane domains. Fractionation of the homogenates from normal aged brains by the same procedure revealed that a substantial proportion of Abeta is localized in the low-density membrane domains.
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